Abstract: | Dynamic stress intensity factors KD were measured by the caustic method and crack propagation velocity ? by the velocity gauge techniques for PMMA poly(methyl methacrylate)] during dynamic crack propagation at various strain rates \documentclass{article}\pagestyle{empty}\begin{document}$ \rm \dot \varepsilon $\end{document} . No definite applied strain rate effects on the dynamic stress intensity factor were observed for applied strain rates ranging from 8.33 × 10?4 to 30/sec; however, the test results do show crack propagation velocity dependency in KD ~ ? relations. The high local strain rate region may be realized at the running crack tip even under the quasi-static loading case of \documentclass{article}\pagestyle{empty}\begin{document}$ \rm \dot \varepsilon $\end{document} = 8.33 × 10?4/sec, since all the crack propagation velocities obtained were greater than 50 m/sec even up to 450 m/sec. |